 For example, copper amine oxidase, catalyzes the oxidative deamination of polyamines, especially putrescine, and releases the ROS mediators hydrogen peroxide and ammonia.Other enzymes thought to play a role in ROS production include xanthine oxidase, NADPH oxidase, oxalate oxidase, peroxidases, and flavin containing amine oxidases.In some cases, the cells surrounding the lesion synthesize antimicrobial compounds, including phenolics, phytoalexins, and pathogenesis related (PR) proteins, including β-glucanases and chitinases.